When was the last time martial law was declared in the us

In the state of Alabama by Governor John Patterson in 1961.

Explanation:

Martial law is the imposition of force on the nation or place by the government. In most cases, martial law suggests the forceful imposition of power or authority by the military over the administration of the place. This may be imposed in cases where there is political unrest or even situations that threaten the very essence of the government of that place.

Though martial law can be declared by the president only, some martial laws were imposed by the governors of specific states for their regions too, depending on the situations which may not cover other areas. The last time any form of martial law has ever been imposed in the United States was in 1961 when the Governor of Alabama, John Patterson over the unrest caused by the Freedom Riders. According to the order, Patterson termed the situation as "a result of outside agitators coming into Alabama to violate our laws and customs a serious emergency, a defiance of the Constitution and laws of Alabama". He then "proclaim a state of qualified martial rule in the city of Montgomery and Montgomery County, Alabama".